Long description illustrating relationship between page box
and sheet

This diagram shows the relationship between the abstract page
box and the target sheet where it will be rendered.

A page box takes up the left side of the diagram. The page
box, which has a thin black border, is labeled "Page box" at
the top. Within the page box, another box labeled "Page area"
is shown, also with a thin black border. The area between the
page box edge and the page area edge is labeled "Margin area".

To the right of this box, three arrows (each labeled
"transfer") are shown pointing to three sheets of different
dimensions. Thus, an abstract page box may be rendered to
a variety of target sheets.